In this work, the photochemistry of luteolinidin, a natural deoxyanthocyanidin, found essentially in mosses and ferns is described. In moderately acidic methanol/water (3:1) solutions the dominant species of luteolinidin is the photoactive trans-chalcone. The system was characterised by steady state irradiation and pulse light excitation experiments as well as by pH jumps. The use of this compound to carry out cycles able to write-lock-read-unlock-erase, is discussed.